body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
    height: 100%;
    width: 100%;
}

header {
    background-color: #333;
    color: #fff;
    padding: 10px 0;
    display: flex;
    align-items: center;
}

.title {
    font-size: 40px;
    margin-left: 50px;
    order: -1;
}

header nav {
    flex: 1;
    text-align: right;
}

header nav a {
    color: #fff;
    text-decoration: none;
    margin-right: 20px;
    margin-top: 50px;
}

.container {
    height: 100%;
    width: 100%;
    padding: 20px;
    display: flex;
}

.left {
    width: 200px;
    /* 将左边导航栏的order设置最小，这样就可以跑到左边 */
    order: -1;
}

.center {
    /* 内容区域自动占满剩余空间 */
    flex: 1;
    padding: 20px;
}

.right {
    width: 200px;
}


textarea {
    width: 100%;
    height: 100px;
    margin-bottom: 10px;
    resize: none;
}

button {
    padding: 5px;
    background-color: #333;
    color: #fff;
    border: none;
    cursor: pointer;
}

button:hover {
    background-color: #555;
}


.sidebar {

    width: 200px;
    position: fixed;
    padding-top: 20px;
}

.sidebar a {
    padding: 15px;
    color: #000;
    text-decoration: none;
    display: block;
}

.sidebar a:hover {
    background-color: #575757;
}


.tab-links {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    border-bottom: 2px solid #ccc;
}

.tab-links li {
    margin: 0 20px;
    padding: 10px 0;
    cursor: pointer;
    position: relative;
}

.tab-links li.active {
    color: #007bff;
    /* 选中时的字体颜色 */
}

.tab-links li.active:after {
    content: '';
    display: block;
    width: 100%;
    height: 2px;
    background: #007bff;
    /* 下划线的颜色 */
    position: absolute;
    bottom: -2px;
    /* 下划线距离文字的高度 */
    left: 0;
}

.user {
    margin-top: 10px;
    margin-bottom: 20px;
    font-size: 20px;
}

.user a {
    text-decoration: none;
    display: block;
}